


Calculates the inner product of vectors X and Y for the case of Gaussian
stationary noise having a specified power spectral density (PSD) Sn(f).
Input: fftY = Normlized FFT vector of the phase term of quadrature template
fftXbyPSD = FFT vector of data divided by PSD Sn(f) and
multiplied by the frequency amplitude term A.
Output: innProd: inner product value
The scalar normalization factor (1/N) is derived from Parseval's theorem.